Lacustrine ostracodes in the Late Pleistocene Sunnybrook diamicton of southern Ontario, Canada

1987 ◽  
Vol 24 (11) ◽  
pp. 2330-2335 ◽  
Author(s):  
J. A. Westgate ◽  
F.-J. Chen ◽  
L. D. Delorme
Keyword(s):  
Late Pleistocene ◽  
Laurentide Ice Sheet ◽  
Silty Clay ◽  
Southern Ontario ◽  
Quaternary Stratigraphy ◽  
Clayey Silt ◽  
Low Diversity ◽  
Excellent Preservation

Two opposing interpretations have been made on the depositional origin of the Late Pleistocene Sunnybrook diamicton in the Metro-Toronto region of southern Ontario. The traditional view holds this deposit to be a till, but more recent arguments advocate a glaciolacustrine origin by suspension deposition and ice rafting.The discovery of a low-diversity ostracode fauna consisting of Candona subtriangulata, Candona caudata, and Darwinula stevensoni in the Sunnybrook diamicton suggests a lacustrine origin. Excellent preservation of thin, fragile shells and a mixture of juveniles and adults in sediments of varying texture—clayey silt to silty clay—indicate that there has been little winnowing or selective sorting and that the ostracodes are in situ. Indications are that the Sunnybrook diamicton was deposited in a large, deep, and cold lake.These new palaeontological observations call for a reassessment of the Quaternary stratigraphy of the Ontario Basin and suggest that the Laurentide Ice Sheet in the eastern Great Lakes region was less extensive during the early part of the Wisconsin Glaciation than previously assumed.

scholarly journals New Dates from Submerged Late Pleistocene Sediments in the Southern Sea of Galilee, Israel

Radiocarbon ◽  
2001 ◽  
Vol 43 (3) ◽  
pp. 1167-1178 ◽  
Author(s):  
D Nadel ◽  
S Belitzky ◽  
E Boaretto ◽  
I Carmi ◽  
J Heinemeier ◽  
...  
Keyword(s):  
Late Pleistocene ◽  
Lacustrine Sediments ◽  
High Water ◽  
Dead Sea ◽  
Water Levels ◽  
Hunter Gatherers ◽  
Water Rise ◽  
Excellent Preservation ◽  
Organic Remains

Unusual low water levels in the Sea of Galilee (Dead Sea Fault, Israel) have caused the recent exposure of submerged Late Pleistocene prehistoric sites and lacustrine sediments along the southern shores of the lake. The Ohalo II site is a large fisher-hunter-gatherers camp with in-situ brush hut floors, hearths, and a human grave. The site is radiometrically dated by 25 charcoal dates to 19,430 BP (average, uncalibrated). The archaeological remains include quantities of excellently preserved organic remains. These would not have been preserved without a rapid rise of lake level immediately after the occupation, covering the remains with silts and sand. Recently a concentration of eight tree trunks were found about 1.5 km south of Ohalo II, of which five trunks were identified as Salix species and dated as a single accumulation at about 16,100 BP. The trunks, too, had to be submerged quickly together to ensure excellent preservation. The camp and the trunks were found at −212/−213 m, almost 4 m below modern high water levels. We suggest that the finds represent two separate episodes of deposition during low lake levels, almost 3,000 radiocarbon years apart, each followed by an abrupt water rise. It is possible that climatic changes caused the observed fluctuations, though earthquakes (blocking or lowering the Jordan outlet, for example) cannot be ruled out.

Behavior of Instrumented Omega Pile in Porous Soil

2014 ◽  
Vol 1030-1032 ◽  
pp. 732-735
Author(s):  
Paulo J.R. Albuquerque ◽  
Osvaldo de Freitas Neto ◽  
Jean R. Garcia
Keyword(s):  
Tropical Soils ◽  
Soil Parameters ◽  
Silty Clay ◽  
Geometric Conditions ◽  
Viable Solution ◽  
Clayey Silt ◽  
Load Tests ◽  
Numerical Finite Element ◽  
Experimental Values

Results obtained from in-situ load tests carried out on omega displacement piles sunk in a porous, lateritic and unsaturated soil deposit, are analyzed in this paper. Three slow-maintained load tests were performed on deep instrumented piles with a diameter of 0.37 m and around 12 m long. The soil deposit consists of a superficial, silty clay “porous” layer 6 m thick. Under this layer there is a lateritic stratum 10 m thick, geotechnically consisting of a residual clayey silt. The results of the field load tests yielded a maximum pile load (average for the tests) of 1428 kN, which is twice as high as corresponding experimental values from standard bored piles with similar geometric conditions. Numerical finite element analyses, were performed in order to back-analyze the geotechnical soil parameters for a post-execution pile condition. The results permitted a better understanding of the improvement of the subsoil given the intrinsic execution characteristics of this particular pile. It was also possible to note that omega displacement piles have great potential to become an economically viable solution in tropical soils, given the enhanced behavior of such piles when compared to alternative techniques.

DETERMINING THE TIMING AND RATE OF SOUTHEASTERN LAURENTIDE ICE SHEET THINNING USING IN-SITU 10BE DIPSTICKS

2018 ◽  
Author(s):  
Christopher T. Halsted ◽  
◽  
Jeremy D. Shakun ◽  
Lee B. Corbett ◽  
Paul R. Bierman ◽  
...  
Keyword(s):  
Ice Sheet ◽  
Laurentide Ice Sheet

scholarly journals In Situ Shear Test for Revealing the Mechanical Properties of the Gravelly Slip Zone Soil

Sensors ◽  
2020 ◽  
Vol 20 (22) ◽  
pp. 6531 ◽  
Author(s):  
Zongxing Zou ◽  
Qi Zhang ◽  
Chengren Xiong ◽  
Huiming Tang ◽  
Lei Fan ◽  
...  
Keyword(s):  
Mechanical Property ◽  
Plastic Deformation ◽  
Shear Test ◽  
Slip Zone ◽  
Three Gorges Reservoir Area ◽  
Silty Clay ◽  
Sigmoid Function ◽  
In Situ Test ◽  
Deformation Stage

Slip zone soil is usually composed of clay or silty clay; in some special geological environments, it contains gravels, which make the properties of the slip zone soil more complex. Unfortunately, in many indoor shear tests, gravels are removed to meet the demands of apparatus size, and the in situ mechanical property of the gravelly slip zone soil is rarely studied. In this study, the shear mechanical property of the gravelly slip zone soil of Huangtupo landslide in the Three Gorges Reservoir area of China was investigated by the in situ shear test. The test results show that the shear deformation process of the gravelly slip zone soil includes an elastic deformation stage, elastic–plastic deformation stage, and plastic deformation stage. Four functions were introduced to express the shear constitutive model of the gravelly slip zone soil, and the asymmetric sigmoid function was demonstrated to be the optimum one to describe the relationship of the shear stress and shear displacement with a correlation coefficient of 0.986. The comparison between the in situ test and indoor direct shear test indicates that gravels increase the strength of the slip zone soil. Therefore, the shear strength parameters of the gravelly slip zone soil obtained by the in situ test are more preferable for evaluating the stability of the landslide and designing the anti-slide structures.

Evaluation on Features of Soft Foundation Engineering and Bearing Layer of Pile in Jiaxing City

2011 ◽  
Vol 90-93 ◽  
pp. 217-221
Author(s):  
Jin Long Zhou ◽  
Qiao Li ◽  
Wei Zhong Cai
Keyword(s):  
Soil Mass ◽  
Shallow Foundation ◽  
Silty Clay ◽  
Foundation Engineering ◽  
Foundation Soil ◽  
Cone Tip Resistance ◽  
Soft Foundation ◽  
Tip Resistance ◽  
Bearing Layer

Through the investigation into composition of major shallow foundation soil mass and the correlation of mechanical indicators in this study, the regression equation of mechanical indicators of the features of local foundation soil mass and the data of in situ testing was obtained. Based on massive quantities of exploration materials, this study analyzed engineering features, distribution status, and the feasibility of silty clay to be used as the bearing layer of the pile in Layer ④2 . The analytical results showed that the silty clay with the uniform depth of over 3.5m and the cone tip resistance in static sounding of over 400MPa could be used as bearing layer of the pile. This study could provide the reference for the accurate understanding of the engineering features of soil mass, and the design and evaluation of foundation in Jiaxing City.

scholarly journals A Leaf Point Documents Hunting with Spears in the Middle Paleolithic at Hohle Fels, Germany

2021 ◽  
Vol 2021 (30) ◽  
Author(s):  
Veerle Rots ◽  
Justin Coppe ◽  
Nicholas Conard
Keyword(s):  
Life History ◽  
Evolutionary Development ◽  
Functional Study ◽  
Middle Paleolithic ◽  
Projectile Technology ◽  
Excellent Preservation ◽  
The Rich ◽  
Pointed End ◽  
The University

During the 2020 season at Hohle Fels Cave in the Ach Valley of southwestern Germany the excavation team from the University of Tübingen recovered a bifacial leaf point in archaeological horizon (AH) X. This horizon is the fifth deepest of the Middle Paleolithic horizons at the site and is located roughly 120 cm beneath the base of the rich Aurignacian layers of the cave. The new leaf point, or Blattspitze in German, is the first artifact of its kind found in situ in the Swabian caves since Gustav Riek’s excavation at Haldenstein Cave near the source of the Lone River recovered two leaf points in excellent preservation in 1936. The new find allowed our team to conduct the first techno-functional study of a freshly recovered leaf point from the European Middle Paleolithic. This study demonstrates that the leaf point was hafted at the less pointy end of the artifact. The leaf point bears clear damage to the pointed end of the artifact that occurred during a hunting episode. A Neanderthal knapper further damaged the tool during an attempt to resharpen and rejuvenate the tool. This damage was likely the reason the knapper discarded the leaf point at Hohle Fels. This result and a re-examination of the two leaf points from Haldenstein Cave indicate that late Neanderthals used Blattspitzen for hunting large game. The current results do not explicitly prove that spears with hafted leaf points were always thrown or used as thrusting spears, and one can easily imagine scenarios in which a weapon of this kind could be used in both ways. Ideally, the ongoing excavation at Hohle Fels will recover more leaf points, which will give us the opportunity to document the technological variability of this kind of tool with regard to their manufacture, function and life history. We also view the current research at Hohle Fels as an excellent opportunity to gain a better and more strongly contextualized understanding of the technological system linking lithic, botanical and osseous technologies during this phase of the Middle Paleolithic. This paper also considers the place that hafted leaf points have within the broader evolutionary development of hunting and projectile technology.

Languages Past and Present: Archaeological Approaches to the Appearance of Northern Iroquoian Speakers in the Lower Great Lakes Region of North America

2008 ◽  
Vol 73 (3) ◽  
pp. 441-463 ◽  
Author(s):  
Scott W. J. Martin
Keyword(s):  
Great Lakes ◽  
First Nations ◽  
Great Lakes Region ◽  
Southern Ontario ◽  
Past Half Century ◽  
Archaeological Materials ◽  
First Millennium ◽  
Spread Of Agriculture ◽  
Demic Diffusion

Archaeological accounts of the spread of agriculture tend to favor either (im)migration/demic diffusion or in situ development/stimulus diffusion. Having moved away from the early twentieth-century's community-wide migration model for Iroquoian origins in the Lower Great Lakes region and southern Ontario in particular, orthodox archaeological belief over the past half-century had come to place Northern Iroquoian speakers in the area since at least 2,000 years ago and likely much earlier. In what appear to be modified versions of the older migrationist arguments, contemporary thought within archaeology once more seems to allow that wholesale relocations were responsible for bringing farming into the region. It has been suggested, for example, that Northern Iroquoian speakers entered southern Ontario as recently as the early or middle centuries of the first millennium A.D. In this paper, I recount the routes this debate has taken and show that the appearance of maize (Zea mays) agriculture, alongside a few other materials, has come to be bound up with documenting the arrival of Northern Iroquoian-speaking communities. I conclude by reiterating the cautions advised by a number of researchers for how we read past ethnicity from archaeological materials and the role this plays in contemporary political discourse between First Nations and others.

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